Originally Posted by Al.canoe

I believe I would have had similar results just due to those high fat sandwiches. My digestive system can't tolerate that kind of fat load when I'm doing (or shortly after) long duration strenuous exercise. It's also not recommended by all my cycle training references as the fat inhibits the repleshment of glycogen. You want high carb (low fat, low protein) nutrition during, and for two hours after, the exercise.

As far as electrolytes are concerned, you need several and in amounts of each driven by you fitness and exercise levels. One of Chris Carmichael's books has all this stuff down to amounts calculated by body weights. I can't be sure of the title as my copy is loaned out, but I think it's something like The Ultimate Ride.

Hyponatriumia is in fact insufficient intake of electrolytes for the amount of water intake.

Al